Trommel equipment is widely used for sorting material by size in various industries including construction, waste disposal, landscaping, and building demolition. It is also used by aggregate producers. Trommel screens are cylindrical in shape, open at both ends, and in use are rotated. The trommel is inclined, so that material naturally tends to travel from the higher end to the lower end. The material to be processed is dumped into the higher end of a trommel screen and rotation causes the material to tumble towards the lower end. Some of the material, the ‘fines’, falls down through the trommel screen and the balance, the coarse material, is discharged out the lower end.
Portable trommels are known. Conventional portable trommel equipment typically comprises a rotary trommel, an input conveyor, and a fines conveyor. These are mounted together on chassis, which is provided with wheels at one end and a “fifth wheel” at the other, for connection to a conventional tractor unit. The input conveyor serves to feed the trommel with materials that are deposited on it. The fines conveyor collects ‘fines’ falling through the trommel screen, and can extend the length of the machine from underneath the trommel to a discharge end.
In order to stockpile screened materials or direct them into a transporter container, typically a separate stacking conveyor must be used. This additional conveyor must be positioned accurately relative to the trommel equipment such that it properly receives screened materials from the fines conveyor. The use of a separate stockpiling conveyor results in substantial costs associated with installing and transporting an additional piece of equipment. These costs can result in trommel machines being inconvenient or impractical for many applications.
Once a stockpiling conveyor has been configured for operation with a trommel machine, its position is fixed and it is not usually practical to adjust its position. Hence, the size of a stockpile that it can make is limited. A tractor or loader is then required to remove processed materials from the stockpile at regular intervals. The processed material is transported to a separate ground area for storage or deposited into a truck. This extra step requires the use and operation of costly loading equipment.
By its very nature, a portable trommel is intended to be frequently and readily moved between different locations. With current portable trommels it is often necessary to provide a stockpiling conveyor. This requires transportation of two separate pieces of equipment. Also, setting up the two pieces of equipment and ensuring they are properly aligned can take from 2 to 4 hours. This results in considerable additional cost.
Further, the material stockpile must be continually serviced by loading equipment in order to prevent the pile from exceeding its maximum height and so that the trommel may process a constant amount of material feed. Over a period of a day, a substantial amount of material must be removed from the fixed stockpile area underneath the stockpiling conveyor. In order to maintain operation of the trommel equipment at an efficient level, two tractors or loading units are required.
Accordingly, there is a need for a stockpiling arrangement for a portable trommel machine, which provides a stockpiling facility and reduces equipment and set up costs as much as possible. Preferably, such an arrangement should also operate as a loader and be capable of rapidly changing from stockpiling to depositing processed materials into a truck or other transport vehicle. Finally, there is a need for a trommel machine which can stack a larger volume of material than is currently possible, without substantially interrupting or reducing the efficient operation of the trammel equipment. Finally, any such modification should still enable a portable trommel to be transported readily on ordinary roads, i.e., it should not be of excessive height or width.